1. Field of the Invention
The present invention is directed generally to lock mechanisms, and more specifically, to lock mechanisms that include features that permit simple and efficient access to pin assemblies and recombination of the lock mechanisms.
2. Description of the Related Art
Lock and key mechanisms have existed relatively unchanged for hundreds of years. While improvements have been made, the fundamental concept remains the same. One such lock mechanism is referred to as a pin-tumbler cylinder lock. In this type of lock, an outer housing has a cylindrical opening in which a cylindrical plug is housed. To open the lock, the cylindrical plug must rotate. The plug generally has a key slot (or “keyway”) at one end to allow a key to enter the plug and a cam or lever at the other end which may activate a mechanism to retract a locking bolt. A plurality of holes are drilled vertically into the plug and contain key pins of various lengths which may be shaped to permit a key to slide over them easily.
Above each key pin is a corresponding set of driver pins that are loaded by springs. Some locks may have only one driver pin for each key pin, but other locks requiring multi-keyed entry (e.g., a master key) may have extra driver pins and/or key pins known as spacer pins. The outer housing has several vertical shafts or pin chambers, which hold the spring-loaded pins. When the plug and outer housing are assembled, the pins are pushed down into the plug by the springs. The point where the plug and cylinder meet is called the shear point. When a proper key is inserted into the key slot of the plug, the key pins rise causing them to align with the shear point, allowing the plug to rotate and the lock to open. As can be appreciated, when no key or an improper key is in the key slot, the driver pins straddle the shear point, preventing the plug from rotating.
The springs and pins may be positioned in the pin chambers of an outer housing and retained by a cover. For example, some locks use a cover that is permanently crimped over the set of springs on an outer housing. In these types of locks, the loading and unloading of pins and springs is performed by removing the cylindrical plug, not the cover. Other locks may use individual set screws or caps to secure the pins and springs inside the outer housing. These types of locks may require special tools to remove the caps or screws. Further, locks having individual caps or screws over each pin chamber may reduce the dimensions of the pin chambers, may be difficult or time consuming to remove, or may have other shortcomings. Therefore, it can be appreciated that there is a need for an improved lock mechanism that allows for simple and efficient loading and unloading of springs and pins from pin chambers. The present disclosure describes such a mechanism, which may provide these and other advantages as is described in the detailed description and accompanying figures.